You can walk for days without eating, but two days without water during intense physical exertion can be fatal. On the trail, water management is an absolute priority combining logistics, physics, and biology. Never trust a stream solely because it looks transparent: bacteria, viruses, and protozoa (like Giardia) thrive in seemingly idyllic mountain waters.
### Different Treatment Methods To make water safe to drink, several options are available, each with its pros and cons:
* **Hollow-fiber filters (e.g., Sawyer or Katadyn):** Fast and lightweight, they mechanically remove 99.99% of bacteria and protozoa. However, they do not protect against viruses (rarely an issue in Europe, but crucial elsewhere). * **Chemical purifiers (chlorine or chlorine dioxide tablets):** Ultralight and effective against everything, including viruses. The main downside is the waiting time (30 mins to 4 hours) and a distinct chemical taste. * **Boiling:** Bringing water to a rolling boil for one full minute kills absolutely all pathogens. It is the ultimate foolproof method, but it consumes a lot of stove fuel.
"In the mountains, upstream water isn't automatically pure. A flock of sheep grazing a kilometre higher up is enough to contaminate an entire stream network."
### Anticipating and Reading the Map The basic safety rule is to plan your water resupply points in advance. Topographical maps are your best friend: locate marked springs, stable rivers, and mountain huts. Be cautious in late summer, though, as many small streams indicated on maps can dry up completely.
Always check with locals or mountain hut wardens before setting off if the season has been particularly dry. Finally, always keep a safety reserve of half a litre — water you don't touch unless your schedule gets seriously delayed.